simpleold

Hi there guys well I inherit a 1972 Oldsmobile cutlass, with an olds 350 just finished today doing the engine swap to an olds 455, i kept the th350 transmission, ill just use it till it goes, then ill upgrade the internals on the transmission, anyway I just finish doing the engine break in, 30 minutes around 2000 2500 rpm, I was a bit hesitant about the engine overheating, i read some stories of 455 overheating so i upgraded the old fan clutch to a Hayden Automotive 2797 severe duty fan clutch, well during engine break in, the engine did not go over 150 degrees for the full 30 minutes it took a good 10 minutes for the gauge to actually start moving, this hayden 2797 really moves air, my question is will i need to do another engine break in for the engine to get to a normal temperature, I don't know how this fan clutch will work once I start driving the car, however I don't think the engine got to a normal operating temperature range during break in any suggestions on this matter? should i keep the Hayden 2797 or downgrade to something heavy duty and not severe duty? i have not driven the car yet, need to change the oil and zinc that i added for the break in. will be adding some 10w 30 ac delco engine oil tomorrow , any help on this matter?

olds 307 and 403

Get a temp gun, make sure that is the actual temperature. The 455 is usually a hot runner if anything.

cutlassefi

Don't use Diesel oils, too much detergent in them.
Use a real break in oil or Valvoline VR-1.

scottv442

if your engine thermostat opened and was flowing anti-freeze or water thru the rad and engine, then your engine was at operating temperature.